Flood Potential Outlook
Issued by NWS Bismarck, ND

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FGUS73 KBIS 141511
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NDC001-007-011-015-021-025-029-031-033-037-041-043-045-047-051-053-
055-057-059-061-065-083-085-087-089-093-103-105-161400-

Probabilistic Hydrologic Outlook
National Weather Service Bismarck ND
1011 AM CDT Thu Mar 14 2024

...SPRING FLOOD AND WATER RESOURCES OUTLOOK...

This Spring Flood and Water Resources Outlook is for the James and
Missouri basins of North Dakota, covering the period of 16 March
through 14 June, 2024. This is the third and final edition of the
Spring Flood and Water Resources Outlook. On 28 March, the NWS will
revert back to routinely issuing of flood probabilities on, or
around, the fourth Thursday of every month.

The following message has four sections. The first provides some
text on the highlights of this outlook and conditions affecting the
local hydrology. The second section gives the current and historical
risks of flooding as determined by the Ensemble Streamflow Forecast
model of the National Weather Service. The third section gives the
current probabilities for reaching flood stage at the listed
forecast locations. And finally, the fourth section covers the risk
of the river sites falling below the listed stages.

...Flood Outlook Highlights...
Given the unseasonably warm weather over the past week, the Missouri
and James river basins of North Dakota are in an active melt pattern
that is currently removing what little snow remains on the
countryside. No damaging high water is expected and the below
probabilities are largely in effect for once the current melt
pattern is complete. As such, the probabilities below largely
represent the risk posed by spring rains. Accordingly, as the wet
ground surface continues to thaw, these probabilities reflect below
normal to well below normal risks of widespread flooding. However,
if history is any lesson, a few examples of minor flooding due to
heavy rains cannot be ruled out as they commonly occur in late
spring.

Perhaps the greater risk going into spring continues to be the
existing long-term trend of below normal precipitation. If this
trend continues, increased and expanded drought designations are a
real concern going forward as temperatures increase and soils dry
out.

...Missouri and Yellowstone Rivers...
In western North Dakota the Missouri and Yellowstone rivers above
Lake Sakakawea are back down to normal water levels for this time of
year despite having recently experienced modest runoff.

The overall snowpack on the plains and headwaters area of Montana
continues to trend well below normal for this time of year, and
remains in contention for the lowest observed Snow-Water Equivalent
(SWE) going into spring for the Missouri and Yellowstone rivers in
the past 30 years.

The ice on the Missouri River below Garrison Dam has now eroded to
well south of the Bismarck and Mandan area. Given the short-term and
mid-term temperature forecasts and outlooks, this signals the end of
ice jam related high water along the Missouri River below Garrison
Dam even though there will be at least some ice yet to hit the
Missouri River from upstream tributaries.

...Snowpack Conditions...
Snowpack across the Missouri and James River basins of North Dakota
is largely melted and making its way to local streams. While areas
protected from lengthy direct sunlight during the day still have
minor amounts of snow, there is not enough volume in that hidden
snow to pose a threat of flooding by itself.

...Current Drought Conditions...
A steady, but slow expansion of D0 (Unusually Dry) continues to
plague much of North Dakota and the Northern Great Plains. A
continuation of the dry pattern in place will increase wildfire and
drought concerns going into spring as the ground thaws and the
region enters its growing season.

...Reservoirs and Natural Wetlands...
Despite an overall snow deficity across most of the state, runoff
due to a wet and frozen ground surface has been remarkable at times.
Most small livestock dams and natural wetlands are near normal for
early spring water levels. Larger water impoundments though are at
greater risk of below normal water levels going into spring and
summer.

...Soil Conditions...
Soil moisture values across the Missouri and James basins are
generally near normal going down to near 40 inches (100 cm), but the
ground surface is much wetter than normal due to early winter rain
and melting snow. This wet and frozen ground surface will
increasingly thaw and allow future precipitation to more readily
infiltrate into the ground.

...Weather Outlook...
The Climate Prediction Center 6-10 and 8-14 day outlooks favor below
normal temperatures and above normal chances for precipitation. That
generally carries the state through the remainder of March, however
the weeks 3-4 outlooks bring back a fairly strong favoring of above
normal temperatures with a slight to strong favoring of below normal
precipitation. Looking longer term at the three-month outlook for
March, April, and May...a favoring for above normal temperatures
with precipitation placed in the equal chances category for above
normal, near normal, or below normal precipitation.

...Ice Conditions...
Ice is quickly waning across most of North Dakota, although the
northernmost areas are somewhat slower to see degradation of its ice.
Many, but not all, small streams in the southern half of North
Dakota area already nearly free of ice. Ice on the small lakes and
natural wetlands continues to soften and degrade as runoff arrives.

In Table 1 below, the current (CS) and historical (HS) or normal
probabilities of exceeding minor...moderate...and major flood stage
are listed for the valid time period.

CS values indicate the probability of reaching a flood category
based on current conditions.

HS values indicate the probability of reaching a flood category
based on historical or normal conditions.

When the value of CS is greater than HS...the probability of
exceeding that level is higher than normal. When the value of CS is
less than HS...the probability of exceeding that level is lower
than normal.

...Table 1--Probabilities for minor...moderate and major flooding...
                     Valid Period: 03/16/2024  - 06/14/2024

                                       :    Current and Historical
                                       :     Chances of Exceeding
                                       :       Flood Categories
                                       :      as a Percentage (%)
                      Categorical      :
                   Flood Stages (FT)   :   Minor    Moderate   Major
Location           Minor   Mod   Major :  CS   HS   CS   HS   CS   HS
--------           -----  -----  ----- : ---  ---  ---  ---  ---  ---
:Pipestem
Pingree             11.0   13.0   15.0 :  <5   12   <5   <5   <5   <5
:James River
Grace City          12.0   14.0   15.0 :  <5   15   <5    9   <5    8
LaMoure             14.0   16.0   18.0 :  <5   17   <5    8   <5   <5
:Missouri River
Williston           22.0   24.0   26.0 :   7   42   <5   27   <5    8
:Cannonball River
Regent              22.0   24.0   26.0 :  <5   <5   <5   <5   <5   <5
:Cedar Creek
Raleigh             12.0   14.0   16.0 :  <5    9   <5    5   <5   <5
:Cannonball River
Breien              10.0   20.0   23.0 :  12   58   <5   <5   <5   <5
:Beaver Creek
Linton              12.0   14.0   16.0 :  <5   45   <5   31   <5   13
:Little Muddy River
Williston           10.0   12.0   14.0 :   8   70   <5   42   <5   10
:Little Missouri River
Marmarth            18.0   23.0   30.0 :  <5    6   <5   <5   <5   <5
Medora              15.0   18.0   20.0 :  <5   24   <5    8   <5    6
Watford City        20.0   24.0   30.0 :  <5   14   <5    5   <5   <5
:Knife River
Manning             15.0   17.0   20.0 :  <5   26   <5   <5   <5   <5
:Spring Creek
Zap                 14.0   18.0   20.0 :   9   31    6   15   <5    8
:Knife River
Hazen               21.0   24.0   25.0 :  14   43    8   31    5   26
:Heart River
Mandan              27.0   33.0   38.0 :  <5   19   <5   <5   <5   <5
:Apple Creek
Menoken             15.0   16.0   17.0 :  26   58   16   55   <5   34

Legend
CS = Conditional Simulation (Current Outlook)
HS = Historical Simulation
FT = Feet

In Table 2 below...the 95 through 5 percent columns indicate the
probability of exceeding the listed stage levels (FT) for the valid
time period.

...Table 2--Exceedance Probabilities...

                              Chance of Exceeding Stages
                                 at Specific Locations
                           Valid Period: 03/16/2024  - 06/14/2024
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Pipestem
Pingree               5.2    5.2    5.2    5.2    5.6    7.1    8.4
:James River
Grace City            4.3    4.3    4.3    4.4    5.5    6.3    6.7
LaMoure               7.6    7.6    7.6    7.6    8.1    9.1   10.6
:Missouri River
Williston            17.6   18.1   18.9   19.4   20.3   21.8   22.8
:Cannonball River
Regent                5.2    5.2    5.3    6.5    7.9    8.7    8.9
:Cedar Creek
Raleigh               0.9    1.0    2.0    2.9    4.5    5.4    5.7
:Cannonball River
Breien                2.3    2.5    3.5    5.6    8.1   10.2   10.6
:Beaver Creek
Linton                4.3    4.4    4.6    5.5    6.6    9.8   11.4
:Little Muddy River
Williston             4.3    4.3    5.3    7.1    8.4    9.6   11.5
:Little Missouri River
Marmarth              1.1    1.1    1.1    1.4    5.1    8.2   11.2
Medora                1.5    1.5    1.5    2.4    5.5    8.6   11.8
Watford City          7.1    7.1    7.1    8.0   10.0   13.0   15.1
:Knife River
Manning               6.4    6.4    6.4    8.3    9.5   12.6   13.6
:Spring Creek
Zap                   4.9    5.0    5.8    7.2    8.7   12.0   19.0
:Knife River
Hazen                 2.9    2.9    4.9    8.9   14.6   23.7   25.2
:Heart River
Mandan               12.6   12.6   13.5   15.5   21.3   23.5   25.7
:Apple Creek
Menoken               6.4    6.4    7.0    8.9   15.1   16.7   16.9

In Table 3 below...the 95 through 5 percent columns indicate the
probability of falling below the listed stage levels (FT) for
the valid time period.

...Table 3--Nonexceedance Probabilities...

                            Chance of Falling Below Stages
                                 at Specific Locations
                           Valid Period: 03/16/2024  - 06/14/2024
LOCATION              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Pipestem
Pingree               5.1    5.1    5.1    5.1    5.1    5.1    5.1
:James River
Grace City            4.2    4.2    4.2    4.1    4.1    4.1    4.1
LaMoure               7.4    7.3    7.0    6.9    6.9    6.8    6.8
:Missouri River
:Cannonball River
Regent                5.0    5.0    5.0    5.0    5.0    4.9    4.9
:Cedar Creek
Raleigh               0.3    0.3    0.3    0.3    0.3    0.3    0.3
:Cannonball River
Breien                2.1    2.1    2.1    2.1    2.1    2.0    2.0
:Beaver Creek
Linton                4.2    4.2    4.2    4.2    4.2    4.2    4.2
:Little Muddy River
Williston             4.3    4.3    4.3    4.3    4.3    4.3    4.2
:Little Missouri River
Marmarth              1.1    1.1    1.1    1.0    0.9    0.9    0.9
Medora                1.4    1.4    1.4    1.3    1.3    1.2    1.2
Watford City          7.0    7.0    7.0    7.0    6.8    6.8    6.8
:Knife River
Manning               6.3    6.3    6.3    6.3    6.2    6.0    6.0
:Spring Creek
Zap                   4.9    4.9    4.8    4.8    4.8    4.8    4.8
:Knife River
Hazen                 0.8    0.7    0.6    0.5    0.3    0.3    0.2
:Heart River
Mandan               11.0   11.0   10.9   10.8   10.8   10.7   10.7
:Apple Creek
Menoken               4.8    4.6    4.5    4.0    3.5    3.3    3.2

These long-range probabilistic outlooks contain forecast values that
are calculated using multiple season scenarios from 30 or more years
of climatological data...including current conditions of the
river...soil moisture...snow cover and 30 to 90 day long-range
outlooks of temperature and precipitation. By providing a range
of probabilities...the level of risk associated with long-range
planning decisions can be determined. These probabilistic
forecasts are part of the National Weather Service`s Advanced
Hydrologic Prediction Service.

Visit our web site weather.gov/bis for more weather and water
information.

The next outlook will be issued on, or around the fourth Thursday of
March.


$$

Schlag


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